The purpose of this method development was to improve conditions for the ethical consideration of participants, collecting reliable data, and achieving results relevant to both practitioners and researchers. In the area of instrumental teaching and learning, these aspects have been little discussed. In this study instrumental teachers were invited to cooperate actively in case studies in which teaching strategies supporting students' musical development were explored. Through participating in the planning, data collection, analyses and communication of results, the practitioners grasped the entire situation of their involvement. Their expertise was made visible. The confidence they developed through this enabled them to critically explore not only strategies which support but also those which obstruct students' learning. The method has also been used in studies on interpretation-finding at different levels. Generally, as a result of their participation, all participants develop a more exploratory approach to strategies of learning and teaching in their respective area.